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Day 18 in Raku with flat lists
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‎2021/day18/day18.raku

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#!/usr/bin/env raku
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# Copyright 2021 Google LLC
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#
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# Use of this source code is governed by an MIT-style
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# license that can be found in the LICENSE file or at
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# https://opensource.org/licenses/MIT.
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#
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# https://adventofcode.com/2021/day/18
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use v6.d;
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use fatal;
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# Input is nested pairs with brackets and digits. Throw away comments and work with a list ints and
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# open/close bracket characters.
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grammar InputFormat {
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rule TOP { <line>+ }
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token ws { <!ww>\h* }
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token num { \d+ }
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token bracket { \[ | \] }
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token thing { [ <bracket> | <num> ] \,? }
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token line { <thing>+ \n }
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}
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class Actions {
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method TOP($/) { make $<line>».made.List }
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method num($/) { make $/.Int }
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method bracket($/) { make $/.Str }
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method thing($/) { make $<bracket>.made || $<num>.made }
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method line($/) { make $<thing>».made.List }
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}
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sub reduce-pair(*@stuff is copy) {
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REDUCE: loop {
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my $depth = 0;
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my $i = 0;
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EXPLODE: for ^@stuff -> $i {
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given @stuff[$i] {
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when '[' {
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$depth++;
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if $depth > 4 {
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my ($first, $second) = @stuff[$i+1, $i+2];
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die "Not ints after $i $first $second @stuff" unless $first ~~ Int && $second ~~ Int;
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die "Not simple pair $i @stuff[]" unless @stuff[$i+3] eq ']';
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my $j = $i;
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$j-- until $j < 0 || @stuff[$j] ~~ Int;
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# say "Setting $j to @stuff[$j] + $first" unless $j < 0;
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# TODO Why does this sometimes fail with "Cannot assign to an immutable value"?
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# @stuff[$j] += $first unless $j < 0;
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@stuff.splice($j, 1, @stuff[$j] + $first) unless $j < 0;
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$j = $i + 3;
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$j++ until $j ≥ +@stuff || @stuff[$j] ~~ Int;
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# say "Setting $j to @stuff[$j] + $second" unless $j ≥ +@stuff;
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# @stuff[$j] += $second unless $j ≥ +@stuff;
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@stuff.splice($j, 1, @stuff[$j] + $second) unless $j ≥ +@stuff;
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@stuff.splice($i, 4, 0);
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next REDUCE;
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}
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}
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when ']' { $depth-- }
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when Int { }
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default { die "unexpected value $_ in @stuff[]" }
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}
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}
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die "Depth $depth after @stuff" unless $depth == 0;
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SPLIT: for ^@stuff -> $i {
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if @stuff[$i] ~~ Int && @stuff[$i] ≥ 10 {
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@stuff.splice($i, 1, ('[', .floor, .ceiling, ']')) given @stuff[$i]/2;
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next REDUCE;
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}
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}
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last REDUCE;
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}
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@stuff
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}
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sub add-pair($a, $b) { reduce-pair(('[', |$a, |$b, ']')).cache }
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sub magnitude(@pair) {
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my @nums;
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for @pair {
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given $_ {
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when Int { @nums.push($_) };
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when '[' { }
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when ']' { @nums.push((@nums.splice(*-2) Z* (3, 2)).sum) } # 3, 2 are specified in the problem
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default { die "unexpected value $_ in @pair[]" };
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}
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}
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die "Nums remainder: @nums[] from @pair[]" unless +@nums == 1;
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@nums[0]
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}
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# Pairs must be reduced using explode and split operations, applying the leftmost explode until
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# there are no more explodes, then the leftmost split until there are no more splits. Explodes
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# happen to any pair that's nested in four other pairs. Splits happen to any int ≥ 10.
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class Solver {
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has Str $.input is required;
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has $.parsed = InputFormat.parse($!input, :actions(Actions.new)) || die 'Parse failed';
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has @.lines = $!parsed<line>».made;
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}
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# Add (wrap in a pair) all lines in the input, then determine the recursive magnitude:
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# 3 * first value + 2 * second value.
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class Part1 is Solver { method solve( --> Str(Cool)) { magnitude(@.lines.reduce: &add-pair) } }
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# Determine the maximum magnitude of adding any two pairs in the input, noting that addition is
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# not commutative.
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class Part2 is Solver {
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method solve( --> Str(Cool)) { (@.lines X @.lines).map({magnitude(add-pair($_[0], $_[1]))}).max }
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}
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class RunContext {
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has $.input-file;
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has $.input;
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has %.expected is rw;
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has @.passed;
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method run-part(Solver:U $part) {
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my $num = $part.^name.comb(/\d+/).head;
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my $expected = $.expected«$num» // '';
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say "Running Day18 part $num on $!input-file expecting '$expected'";
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my $start = now;
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my $solver = $part.new(:$!input);
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my $result = $solver.solve();
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my $end = now;
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put $result;
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"Part $num took %.3fms\n".printf(($end - $start) * 1000);
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@!passed.push($result eq 'TODO' || $expected && $expected eq $result);
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if $expected {
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if $expected eq $result {
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say "\c[CHECK MARK] PASS with expected value '$result'";
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} else {
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say "\c[CROSS MARK] FAIL expected '$expected' but got '$result'";
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}
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}
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}
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}
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sub MAIN(*@input-files) {
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my $exit = all();
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for @input-files -> $input-file {
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if $input-file.IO.slurp -> $input {
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my $context = RunContext.new(:$input, :$input-file);
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if (my $expected-file = $input-file.IO.extension('expected')).f {
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for $expected-file.lines {
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$context.expected«$0» = $1.trim if m/part (\d+) \: \s* (.*)/;
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}
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}
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$context.run-part(Part1);
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say '';
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$context.run-part(Part2);
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$exit &= all($context.passed);
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} else {
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say "EMPTY INPUT FILE: $input-file";
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}
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say '=' x 40;
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}
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exit $exit ?? 0 !! 1;
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}

‎2021/day18/input.actual.expected

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part1: 4111
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part2: 4917

‎2021/day18/input.actual.txt

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[[7,[8,[3,5]]],[[[3,6],9],1]]
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[[[[1,7],8],[0,4]],[[[0,9],2],[2,[5,6]]]]
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[[[4,[4,4]],[8,[4,4]]],[[5,4],6]]
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[[[1,[1,3]],[[9,6],1]],[[4,[5,4]],[[4,4],[0,8]]]]
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[[[[6,2],[2,5]],[2,1]],[[1,5],7]]
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[[[[5,0],[2,7]],[[2,5],2]],[2,[3,2]]]
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[[[6,[6,6]],[0,[2,8]]],[[8,[5,6]],[4,5]]]
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[[[6,[3,5]],8],[[2,[7,0]],5]]
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[[[[7,8],[3,6]],[1,6]],[[[4,2],1],[[0,7],[5,6]]]]
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[8,2]
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[[5,5],[[2,[9,1]],8]]
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[[[4,8],[[1,8],2]],[9,2]]
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[2,[[8,[8,3]],[0,6]]]
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[[[6,6],[[6,0],6]],[0,[[3,4],3]]]
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[[[[2,9],[5,9]],[2,[4,3]]],[6,0]]
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[[[6,2],0],[7,7]]
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[[[9,6],5],[2,[[0,1],[5,5]]]]
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[[6,[[0,1],[5,1]]],5]
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[4,[[[4,2],3],[2,[5,0]]]]
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[[[7,9],2],2]
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[[[5,[2,1]],1],[[1,1],[8,5]]]
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[[[[5,9],0],[[1,9],0]],4]
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[[7,[0,5]],[[0,3],[8,2]]]
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[[6,[9,[7,7]]],6]
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[2,[[1,[1,0]],[4,[6,1]]]]
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[[0,6],[[[5,1],6],[[4,7],[8,0]]]]
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[[[1,[4,7]],[0,[1,2]]],[[1,1],[[1,2],[1,3]]]]
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[[8,[3,0]],[3,[1,[8,1]]]]
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[[[7,[4,0]],[[8,7],2]],[[7,[7,3]],7]]
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[3,[[1,7],2]]
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[8,[[[1,5],0],1]]
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[[6,[1,4]],7]
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[[[[2,6],2],8],1]
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[9,7]
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[9,[[[1,1],1],[[3,0],[7,3]]]]
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[[[[8,5],7],[[5,1],[6,4]]],[4,[[7,6],[2,7]]]]
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[[[[8,7],1],0],[[9,9],[[1,0],8]]]
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[[9,[[1,1],7]],[[3,0],4]]
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[[[[8,2],4],[9,[7,9]]],[[0,2],[[3,0],5]]]
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[[[[3,6],3],[[9,7],[0,6]]],[[[4,9],[1,3]],[2,[7,3]]]]
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[[[[3,8],0],[[3,6],5]],[[3,[4,2]],[[6,1],[8,5]]]]
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[[2,7],[[0,0],8]]
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[[[[0,3],7],[2,0]],3]
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[[0,2],[[[3,1],0],[0,0]]]
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[[[[6,1],7],[[8,4],[2,4]]],[[1,6],[2,3]]]
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[[2,[2,[9,1]]],[4,[[0,4],9]]]
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[[[3,[5,6]],7],1]
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[[[3,0],[8,[9,3]]],[[[1,1],1],[6,7]]]
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[[[6,[4,4]],[[1,9],1]],[[[8,1],[9,8]],[[6,3],1]]]
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[[[5,8],[[0,3],[1,7]]],[[[3,2],[4,7]],1]]
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[[5,5],[[[8,3],[6,6]],2]]
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[[[[1,9],[8,5]],[[7,7],8]],[0,[8,[7,4]]]]
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[[6,[4,[4,3]]],[5,[6,[7,2]]]]
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[[0,[[9,0],0]],5]
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[[[[5,6],[1,3]],[[0,5],[7,5]]],[[[0,4],[3,6]],[8,[3,6]]]]
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[[3,[[4,7],[7,0]]],[[[4,1],5],[[6,6],[7,4]]]]
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[[[[4,3],[0,1]],[[7,3],[2,3]]],[[[3,7],[2,2]],[6,5]]]
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[[1,1],[[[1,4],6],[6,[3,9]]]]
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[[[[0,8],[2,0]],5],[4,[[6,1],[2,1]]]]
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[[7,[3,[7,2]]],[[7,9],8]]
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[[[4,[9,8]],[8,[3,2]]],[7,9]]
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[[[4,[4,2]],[5,[0,3]]],[[[4,9],[2,9]],[[1,5],[0,8]]]]
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[[1,[[9,8],0]],[5,[[4,3],5]]]
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[[[[5,1],3],[[2,9],[9,0]]],[1,[6,3]]]
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[[[6,4],[6,1]],7]
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[[4,8],[[7,2],6]]
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[[[5,[4,8]],[[1,7],[2,8]]],[6,[[8,4],[3,5]]]]
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[[5,8],[[[4,0],[6,0]],[5,[6,0]]]]
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[[3,[[5,3],8]],[8,5]]
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[[[2,6],[1,[2,3]]],[[[1,7],[5,7]],[[0,0],[0,5]]]]
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[[0,[[4,3],[3,6]]],[[2,[6,6]],[0,[2,9]]]]
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[[[5,9],[6,2]],[[7,6],8]]
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[[9,2],[1,[[0,5],[5,0]]]]
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[[[3,1],[9,3]],3]
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[[[[2,0],[4,2]],6],[[[5,2],[7,8]],[[0,7],3]]]
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[[7,[[3,9],[6,3]]],[2,[[6,4],3]]]
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[[5,[3,[7,4]]],[[2,5],[0,9]]]
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[3,7]
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[[3,9],[[[4,4],9],[[3,1],7]]]
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[[[[4,0],1],[8,[3,6]]],[[9,[4,4]],[[9,9],9]]]
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[[8,[[8,1],5]],[[[9,1],4],[[8,5],3]]]
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[[6,[[6,3],[3,7]]],4]
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[[[1,[0,8]],9],[[8,5],[3,[0,5]]]]
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[[[[3,1],0],[[8,5],[1,0]]],[0,2]]
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[[2,[4,7]],2]
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[[[2,0],[2,2]],4]
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[4,[[5,8],5]]
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[[[2,[0,5]],[[3,3],[6,6]]],1]
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[[[2,[2,4]],[5,[7,1]]],[3,5]]
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[[2,[9,[3,9]]],9]
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[[[7,[7,1]],[[5,2],1]],[[2,1],[9,[7,3]]]]
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[[4,[4,6]],4]
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[[[4,2],[9,[3,8]]],[[2,4],0]]
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[[[7,[0,3]],4],[[[1,8],4],[[5,1],1]]]
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[[[1,3],3],[[4,9],[[0,0],6]]]
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[[[4,1],0],[[[5,6],[0,8]],[[2,1],1]]]
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[[3,[3,[7,9]]],[[[6,8],8],[[7,9],3]]]
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[[4,[[1,6],[4,6]]],[[1,8],[3,8]]]
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[[[[5,9],2],[[6,7],4]],3]
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[[[[2,1],[1,9]],7],[[[0,9],[0,5]],[[2,5],[5,0]]]]

‎2021/day18/input.example.expected

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part1: 4140
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part2: 3993

‎2021/day18/input.example.txt

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[[[0,[5,8]],[[1,7],[9,6]]],[[4,[1,2]],[[1,4],2]]]
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[[[5,[2,8]],4],[5,[[9,9],0]]]
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[6,[[[6,2],[5,6]],[[7,6],[4,7]]]]
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[[[6,[0,7]],[0,9]],[4,[9,[9,0]]]]
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[[[7,[6,4]],[3,[1,3]]],[[[5,5],1],9]]
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[[6,[[7,3],[3,2]]],[[[3,8],[5,7]],4]]
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[[[[5,4],[7,7]],8],[[8,3],8]]
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[[9,3],[[9,9],[6,[4,9]]]]
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[[2,[[7,7],7]],[[5,8],[[9,3],[0,2]]]]
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[[[[5,2],5],[8,[3,7]]],[[5,[7,5]],[4,4]]]

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